Boost Converter Control for Detecting Momentary Voltage Sags
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power conversion systems face challenges in accurately detecting momentary power failures or voltage sags, leading to unstable operations and false detections, which require tuning for each model and increase design load.
Innovation Solution
A power conversion apparatus with a rectifier, converter unit, smoothing capacitor, current detection unit, voltage detection unit, and converter control unit that calculates a switching command value based on the ratio of rectified voltage to output voltage, allowing for accurate detection of momentary power failures or voltage sags without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a booster circuit controls input current using semiconductor switching element ON/OFF operation, then the rectified output voltage can be raised and converted to direct-current voltage, but a momentary power failure or voltage sag causes overcurrent in the switching element and sudden output voltage changes
Solution Approach 1:
The system performs preliminary detection of abnormality conditions (momentary power failure or voltage sag) by monitoring the switching command value before overcurrent damage can occur. When an abnormality is detected, the control unit preemptively sets a restriction flag to limit the switching command value, preventing the harmful overcurrent condition from developing while allowing the system to recover gracefully.
Solution Approach 2:
The control unit continuously monitors the switching command value and provides feedback to detect abnormalities. When the switching command value exceeds a predetermined threshold, the system detects the abnormal condition and adjusts the switching command value accordingly, creating a closed-loop control system that maintains reliability while preserving power conversion functionality.
2Measurement precision
If existing detection methods monitor current or voltage changes, then abnormalities can be detected, but false detections occur during system activation or stopping, requiring model-specific tuning that increases design load
Solution Approach 1:
The invention changes the detection parameter from raw current or voltage values to the switching command value, which inherently reflects the ratio between rectified voltage and output voltage. This parameter transformation eliminates the need for model-specific tuning because the switching command value naturally adapts to different operating conditions without requiring threshold adjustments for each system configuration.
Solution Approach 2:
The detection method using switching command value is universally applicable across different system models and operating conditions. Unlike current or voltage-based detection that requires separate tuning for each model, the switching command value approach provides a unified detection mechanism that works consistently during activation, normal operation, and stopping phases without requiring model-specific parameters.
3Measurement precision
If the switching command value is calculated based on the ratio of rectified voltage to output voltage, then accurate detection of momentary power failure or voltage sag is enabled without additional detection components
Solution Approach 1:
The switching command value, originally calculated for power conversion control purposes, is repurposed to serve dual functions: maintaining voltage conversion and detecting abnormalities. By monitoring this existing control parameter, the system achieves accurate detection of momentary power failures and voltage sags without adding separate detection circuits, sensors, or components.
Solution Approach 2:
The control system uses its own internal switching command value for self-diagnosis and abnormality detection. The system monitors its own operational parameters and automatically detects abnormalities without requiring external detection devices,实现ing a self-monitoring capability that reduces component count while maintaining detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables easy and accurate detection of momentary power failures or voltage sags, preventing false detections and reducing the likelihood of system shutdowns, while improving responsiveness and reliability during power restoration.
Implementation Method 1
a rectifier configured to rectify an alternating-current voltage supplied from an alternating-current power supply
Implementation Method 2
a converter unit including a reactor connected to an output terminal of the rectifier, a reverse current prevention element connected in series with the reactor, and a switching element connected between the reactor and the reverse current prevention element, and being configured to raise a rectified voltage rectified by the rectifier and output the rectified voltage as an output voltage
Implementation Method 3
a smoothing capacitor configured to smooth the output voltage output from the converter unit
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A power conversion apparatus includes: a rectifier configured to rectify an alternating-current voltage supplied from an alternating-current power supply; a converter unit including a reactor, a switching element, and a reverse current prevention element, and configured to raise a rectified voltage rectified by the rectifier and output the rectified voltage as an output voltage; a smoothing capacitor configured to smooth the output voltage output from the converter unit; a current detection unit configured to detect a reactor current flowing to the reactor; a voltage detection unit configured to detect the output voltage output from the converter unit; and a converter control unit configured to control operation of the switching element of the converter unit. The converter control unit includes a switching command calculation unit configured to calculate a switching command value responsive to a ratio of the rectified voltage to the output voltage in accordance with the output voltage detected by the voltage detection unit and the reactor current detected by the current detection unit, a switching control unit configured to control operation of the switching element in accordance with the switching command value calculated by the switching command calculation unit, and a supply abnormality determination unit configured to determine occurrence of a momentary power failure or a momentary voltage sag in accordance with the switching command value.